The Sukhoi Su-25, which did not have weapons or ammunition on board, crashed Monday evening near the Budyonnosk airbase in an unpopulated area of Stavropol Territory, in southern Russia near its border with Georgia.

The cause was unknown, though state-run Tass news agency, quoting a source, reported the flight data and voice recorders on the plane were found intact. The pilot's identity was not revealed.

The Su-25 is among the planes Russia is using in its air war in Syria. The crash was the first for a Su-25 since a 2013 crash in Russia's Krasnodor Territory. Following Monday's accident, other Su-25s were not grounded, the Tass source said.